I haven't found any information regarding this and I think although not common, it can affect some workflow.
For example:
Pool made with 2 Disks:
Disk A: 8TB with 10GB left holding test.log (1GB in size)
Disk B: 8TB with 5TB used
Say on this A I have a log file currently taking 1GB in size, what happen when my program is running and start writing so much log that makes the log file slowly go up, say it would reach 20GB before it stop. What will happen since Disk A only have 10GB left?